You are most probably exceeding the maximum execution time when trying to retrieve 7000 posts/products, or specifically more than 2000 posts/products.
To be quite honest with you, 7000 posts/products (or even just a list of posts/products) all packed in one single page is not only going to drive you crazy, but anyone visiting your site. I can imagine how long does 2000 posts/products take to load if just a little more exceeds the maximum execution time, 7000 is more than 3 times more.
If I was a new prospective client, you would have lost my business simply by just frustrating me when a extremely long page load.